The technology described herein relates to the display of video data, and methods of encoding and decoding video data.
As is known in the art, the output (e.g. frame) of a video processing system is usually written to an output buffer (e.g. frame or window buffer) in memory when it is ready for display. The output buffer may then be read by a display controller and output to the display (which may, e.g., be a screen) for display, or may be read by a composition engine and composited to generate a composite frame for display.
The writing of the data to the output buffer consumes a relatively significant amount of power and memory bandwidth, particularly where, as is typically the case, the output buffer resides in memory that is external to the video processor.
It is known therefore to be desirable to try to reduce the power consumption of output buffer operations, and various techniques have been proposed to try to achieve this.
One such technique is disclosed in the Applicants' earlier application GB-2474114. According to this technique, each output frame is written to the output buffer by writing blocks of data representing particular regions of the frame. When a block of data is to be written to the output buffer, the block of data is compared to a block of data already stored in the output buffer, and a determination is made as to whether or not to write the block of data to the output buffer on the basis of the comparison.
The comparison is made between a signature representative of the content of the new data block and a signature representative of the content of the data block stored in the output buffer. The signatures may comprise, for example, CRCs which are calculated and stored for each block of data. If the signatures are the same (thus indicating that the new data block and the stored data block are the same (or sufficiently similar), the new data block is not written to the output buffer, but if the signatures differ, the new data block is written to the output buffer.
Although the method of GB-2474114 is successful in reducing the power consumed and bandwidth used for the output buffer operation, i.e. by eliminating unnecessary output buffer write transactions, the Applicants believe that there remains scope for improvements to such “transaction elimination” methods, particularly in the context of video data.